F4‐TCNQ as an Additive to Impart Stretchable Semiconductors with High Mobility and Stability

Abstract

Numerous strategies are developed to impart stretchability to polymer semiconductors. Although these methods improve the ductility, mobility, and stability of such stretchable semiconductors, they nonetheless still need further improvement. Here, it is shown that 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) is an effective molecular additive to tune the properties of a diketopyrrolopyrrole‐based (DPP‐based) semiconductor. Specifically, the addition of F4‐TCNQ is observed to improve the ductility of the semiconductor by altering the polymer’s microstructures and dynamic motions. As a p‐type dopant additive, F4‐TCNQ can also effectively enhance the mobility and stability of the semiconductor through changing the host polymer’s packing structures and charge trap passivation. Upon fabricating fully stretchable transistors with F4‐TCNQ‐DPP blended semiconductor films, it is observed that the resulting stretchable transistors possess one of the highest initial mobility of 1.03 cm2 V−1 s−1. The fabricated transistors also exhibit higher stability (both bias and environmental) and mobility retention under repeated strain, compared to those without F4‐TCNQ additive. These findings offer a new direction of research on stretchable semiconductors to facilitate future practical applications.

Tuning of the elastic modulus of a soft polythiophene through molecular doping

“…1 for chemical structure), resulting in a more stretchable material as evidenced by a higher crack onset strain. 13 A reduction in stiffness upon molecular doping has also been reported for stretch-aligned polymer films or fibers composed of polyacetylene, 5 poly(2,5-dimethoxy-pphenylenevinylene), 14 poly(2,5-thienylene vinylene) 15 and P3HT. 7 Molecular doping of conjugated polymers with a lower stiffness can have an adverse effect on the elastic modulus (Table 1).…”

Tuning Conjugated Polymer Chain Packing for Stretchable Semiconductors

“…[23,24] Recently, molecular solid additives were found to improve the strain tolerance of D-A conjugated polymers, but the charge-carrier mobilities of these films were negatively affected as seen by around one order of magnitude decrease in mobility at 100% strain. [25] To design new packing structure modifiers for realizing better stretchability, more fundamental questions need to be further investigated: (1) How does the existence of designed additives influence the polymer chain packing structure, especially in the crystalline region? (2) What are the possible multiscale deformation mechanisms of the additive-modified conjugated polymers and how are these mechanisms correlated to the chargetransport properties?…”

Ultrasoft and High‐Mobility Block Copolymers for Skin‐Compatible Electronics

“…The conductivity was measured after selected cycle numbers (50, 100, 500, 1000 and 1500) at 0, 25 and 50% strain range. The addition of F4‐TCNQ can induce ductility in DPP‐based polymers, [ 48 ] which might contribute to maintaining electrical functionality while stretching. Still, the conductivity of PDPP‐TT decreased steeply when the film was stretched repeatedly in either parallel (Figure 3e) or perpendicular (Figure 3f) direction.…”